Genetics

• Oompa Loompas generally have gray faces (G) which is dominant. The recessive allele results in an orange face (g). Two heterozygous Oompa’s mate and have babies. What are the possible genotypes and phenotypes of their offspring?1 GG (gray) : 2 Gg (gray) : 1 gg (orange)
• In goats, a recessive gene (ff) causes the goats to ‘faint’ when they are startled. A farmer breeds two goats (that have never fainted) and their first offspring faints two days after its first birthday. What must the parent’s genotypes have been? Ff and Ff
• In humans, tongue rolling is a dominant trait (R). Those with the recessive condition cannot roll their tongues. Bob can roll his tongue, but his mother could not. He is married to Sally, who cannot roll her tongue. What is the probability that their first-born child will not be able to roll his tongue?

  Bob = Rr, Sally = rr

  p(roll) = 1/2
• A round (R) seed plant is dominant to a wrinkled (r) seed plant. What two genotypes, when crossed, will produce offspring that are 50% homozygous dominant and 50% heterozygous?

  Rr x RR
• Crows’ feet can have orange and/or brown markings. When a crow with orange markings is mated with a crow with brown markings, their offspring have both orange and brown spots on the feet. What type of inheritance is happening here?

  Co-dominance
• Rats can have a variety of fur colour controlled by a single gene. When a black-furred rat is crossed with a white-furred rat, all offspring have gray fur. If you cross a gray-furred rat with a black-furred rat. The expected phenotypic ratio of the offspring is 1 FBFB (black) : 1 FBFW (gray). What type of inheritance is happening here?

  Incomplete dominance
• In Snarlymonsters, the number of teeth is under the control of three separate genes. The recessive condition (aabbcc) results in a toothless Snarlymonster, and the dominant condition (AABBCC) results in a Snarlymonster with 6 teeth. There are 5 other possible variations. With this, how many teeth would a Snarlymonster with the genotype AaBbCc have?

  3
• Coat colour in cats is a codominant trait and is also located on the X chromosome. Cats can be black, yellow or tortoiseshell. A tortoiseshell cat has black and yellow splotches. When a female tortoiseshell cat is mated with a black cat, what are the phenotypes of the offspring?

  Males : either black or yellow

  Females : either black or tortoiseshell
• In the human ABO blood type system, the IA and IB alleles are codominant to each other and completely dominant over the i allele. If two parents with type AB blood have children, what are their possible phenotypes?

  1/4 type A : 1/2 type AB : 1/4 type B
• A man with type AB blood and a woman with type O blood have two natural children and one adopted child. Their children have blood types A, B, and O. Which child was adopted?

  The child with type O
• In mice, a spinning behaviour is caused by a dominant gene that affects the mouse's equilibrium. This gene is lethal if two alleles are present. Two "spinning mice" are mated together. What is the phenotypic ratio of the offspring?

  2/3 spinning : 1/3 normal
• An individual with Turner Syndrome has monosomy X. What type of error occurred to cause this difference? In which parent could the error have occurred?

  Nondisjunction

  It could have happened in either parent
• In this pedigree, the affected individuals are shown shaded.  None of the marriage partners from outside these two families are heterozygous for the trait. What is the inheritance pattern for this trait?

  Autosomal recessive

  
• What inheritance is shown in this pedigree?

  Autosomal recessive

  
• In rabbits, gray hair (G) is dominant to white hair (g), and black eyes (B) are dominant to red eyes (b). These two traits are independent of each other. A male rabbit with the genotype GGbb is crossed with a female rabbit with the genotype ggBb. What’s the probability that the gametes produced by the female rabbit will be gb?

  1/2
• In rabbits, gray hair (G) is dominant to white hair (g), and black eyes (B) are dominant to red eyes (b). These two traits are independent of each other. A male rabbit with the genotype GGbb is crossed with a female rabbit with the genotype ggBb. Use a Punnet square to determine the phenotypes and proportions in the offspring. How many of the 16 progenies are grey haired and have red eyes?

  8
• In rabbits, gray hair (G) is dominant to white hair (g), black eyes (B) are dominant to red eyes (b), and the urge to destroy things (D) is dominant over being docile (d). These traits are independent of each other. Two parents heterozygous for these three traits have a litter of 16 baby bunnies. What’s the probability of an offspring being homozygous gg and heterozygous for only one of the other genes?

  8 out of 64
• In the ABO blood type system, the IA and IB are codominant and the i allele is recessive. Individuals with an ii genotype are ‘O’ type blood.Another independently assorting gene that controls blood type is whether an individual is ‘+’ and displays the Rh protein, or ‘-’ who don’t display the Rh protein. + is completely dominant over -. What is the probability of parents who are AO+- and BO- having an AB- child?

  2/16
• In mice, the spinning behavior is caused by a dominant gene that affects the mouse's equilibrium. This gene is lethal if two alleles are present. Two "spinning mice" are mated together. What ratio of progeny will exhibit the spinning behavior?

  2/3
• Which of the following is not a chromosomal systems of sex determination? 

  X-Y system

  haplo-diploid system

  0-Y system

  X-0 system

  Z-W system

  Z-W system
• If a female child has red-green colour blindness then:

  (a)her brother cannot be colour-blind

  (b)only her father was colour blind

  (c)only her mother was colour blind

  (d)her father was colour-blind and her mother was at least a carrier

  d
• True or false: the fur pattern on tortoiseshell and calico cats are a result of genetic mosaicism caused by Y-inactivation.

  false
• True or false: in females, X-inactivation occurs because one of the X-chromosomes is bad.

  false
• An example of gene flow is: the increase in frequency of the genotype for darker skin pigmentation in Scandinavia due to recent immigration (this is also a cause of microevolution)
• intrasexual selection is the selection that occurs between members of the same sex, such as competition for mates. ex. male birds compete for mates
• sexual dimorphism: the difference in size and shape of the sexes of the same species. ex. only male deer have antlers, only male lions have manes
• intersexual selection: when one sex is selected for traits that are beneficial to the other sex. ex. blue-footed booby
• True or false: populations that are evolving can be at Hardy-Weinberg equilibrium

  false
• All of the following are conditions that must be met for the allelic frequencies in a population to remain in the hardy-weinberg equilibrium EXCEPT FOR:

  (a)populations must be large

  (b)populations must be isolated

  (c)no mutations resulting in net changes

  (d)equal reproductive success for all genotypes

  (e)nonrandom mating

  e
• Allopatric speciation: includes physical isolation by mountains, glaciers, deserts etc; can lead to adaptive radiation; is due to a block in gene flow
• True or false: each pair of alleles separates independently for any other pair of alleles during gamete formation is the Law of Independent Assortment

  true
• True of false: Gregor Mendel's experiments succeeded because he used the scientific method

  true
• You want to determine if a yellow seed producing pea plant is homozygous or heterozygous for the trait. You would do a testcross by crossing it with the:

  (a)homozygous dominant plant

  (b)homozygous recessive plant

  (c)heterozygous plant

  (d)either a homozygous recessive or a homozygous dominant plant

  b
• True or false: when mendel bred true-breeding plants together, he noted that the white flower phenotype disappeared in the F1 generation, but reappeared in the F2 generation. He concluded that this was because the purple flower repressed the white flower trait.

  false